A number of methods for the manufacture of methyl isobutyl ketone from acetone and from isopropanol have long been known. Most of the processes known hitherto involve a number of stages. For example, acetone is reacted in the presence of basic condensation catalysts to form a diacetone alcohol, which, after concentration by distillation, is dehydrated by means of suitable catalysts (e.g., phosphoric acid). The mesityl oxide that is thus formed then has to be selectively hydrogenated in another stage of the process to methyl isobutyl ketone.
Strongly acid catalyst, including strongly acid cation exchangers, are used for the direct transformation of acetone to mesityl oxide.
Also known is a vapor phase process, in which methyl isobutyl ketone along with relatively large amounts of diisobutyl ketone can be produced from isopropanol in a single process stage. The catalyst is a mixed catalyst made of copper oxide, magnesium oxide and pumice flour. The transformations and yields are unsatisfactory.
According to another proposal, the three reaction steps (condensation, dehydration and selective hydrogenation) are combined in a single process stage, an alkaline catalyst being used for the condensation, in conjunction with a palladium-containing hydrogenation catalyst. The yields achieved are comparatively poor.
Another one-stage process for the manufacture of methyl isobutyl ketone is performed preferentially in a liquid phase in the presence of a mixture of a strongly acid cation exchanger and a hydrogenation catalyst working selectively on the olefinic double bond, at temperatures of 100.degree. to 150.degree.C, and in the presence of hydrogen. For the continuous performance of the proposal, it is proposed that acetone be sprayed over a solid catalyst made of a mixture of the two catalysts, with a counter-current of hydrogen. Such a solid catalyst can be obtained by compressing equal parts by weight of cation exchanger and 5% palladium on charcoal. Investigation has shown, however, that a combination catalyst prepared in this manner has a completely insufficient mechanical stability. Due to the great differences in the swelling capacity of such ion exchanger resins in relation to water and acetone, briquettes of this kind are rapidly destroyed by slight loading variations, whether due to irregular sprinkling or due to changes in the rate of transformation. Furthermore, the amount of palladium required is very high in comparison to the process of the invention.